what are the differences between nightmare and inferno?

[FoxySellu]

.

[Infected Shogun]

it says so right in the game when you pick it.

harder enemies
less ammo
no auto save

[FoxySellu]

i havent unlocked inferno yet

[Greb]

Damage, enemies are even more aggressive, blah blah. You won't notice much of a difference by the time you finish Nightmare, you'll have the shop items that makes a lot of the difficulty jump irrelevant too I expect.

The biggest difference is the lack of autosaves. You can't continue and you can't rely on autosave to save you if you die. There are plenty of save points despite what the difficulty information says about "reduced typewriters and item boxes" so that's barely an issue but you can only say 5 times or less if you want to achieve an S rank, so you need to spread them out a little more intelligently I guess.

[FoxySellu]

i have only finished hardcore mode, so in nightmare if a zombie gets you one time, your health is in the red?